Means for regulating constant-potential transformers.



No. 635,786. l Patented Oct. 3l, |899. W. A. LAYMAN & F. SCHWEDTMANN.

MEANS FOB REGULATING CONSTANT POTENTIAL TBANSFOHMERS.

(Application led Feb. 27. 1899.)

iimlmmllm 9mm mmmmmmmmm Im.. IIIllmlmmm N `1 mmlmllngmm mmmmmmmmmmmmmmN0. 635,786. Patented Oct. 3|, |899. W. A. LAYMAN & F. SCHWEDTMANN.

MEANS FOR REGULATING CONSTANT POTENTIAL TRANSFORMERS.

(Application led Feb. 27. 1899.)

3 Sheets-Sheet 2.

(No Model.)

401% W W W W W Zze' 3 Sheets-Sheet 3.

Patented Oct. 3|, |899,

W. A. LAYMAN & F. SCHWEDTMANN. MEANS FOR REGULATING CONSTANT POTENTIALTRANSFORMERS.

lullin- (Application led Feb, 27. 1899.\

(No Model.)

UNITED STATES PATENT EricE0 MISSOURI.

MEANS FOR REGULATING CONSTANT-POTENTIAL TRANSFORMERS.

SPECIFICATION' forming part of Letters Patent No. 685,786, dated October3l, 1899.

Application iilcd February 27,1899. Serial No. 707,073. (No model.)

To all whom, t may con/cern:

Be it known that we, NVALDO A. LAYMAN and FERDINAND SOHWEDTMANN,citizens of the United States, residing at the city of St. Louis, Stateof Missouri, have invented a certain new and useful improvement in meansfor deriving and maintaining a constant alternating current in a circuitof varying resistance from the windings of a constant-potentialtransformer, of which the following is a full7 clear, and exactdescription, such as will enable others skilled in the art to which itappertains to make and use the same, reference being had to theaccompanying drawings, forming part of this specification, in

which-- Figure l is a diagrammatic view illustrating our improved meansfor deriving and maintaining a constant alternating current in a circuitof varying resistance from the windings of a constant-potentialtransformer. Fig. l is a plan view of a mutilated gear used inconnection with our improved switch. Fig. 1D is a detail viewillustrating the means for engaging the teeth of said mutilated gearwith its driving-pinion after said pinion has been rotatingidlyin themutilated section of said gear and then reversing its direction ofrotation. Fig. 2 is a diagrammatic view of a modification thereof. Fig.3 is a diagrammatic view of another modiiication ofthe system forcutting in and cutting out coils of the transformer-winding.

rlhis invention relates to a new and useful improvement in means forderiving and maintaining a constant alternating current in a circuit ofvarying resistance from the windings ofacoustantpotential transformerwhich is fed from a constant-potential dynamo.

The invention is designed particularly for use in connection with theoperation of alternating-current arc-lamps which are arranged in series'from the secondary of the transformer. lt will be obvious that thereare other uses to which our invention can be put without in the leastdeparting from the nature and principle of the saine.

Heretofore arc-lamps have been operated with alternating currents invarious ways. "We will refer to a few of these methods for the purposeof distinguishing our present invention therefrom.

The rst application of alternatingcurrents to arc-lighting systems towhich we will refer is that known as the constant-potential multiple7system. By this system lamps operating as individual units were run inparallel between low-tension feeders in the same way as incandescentlamps are now generally used where such incandescent lamps are used forcommercial lighting. The amount of current taken by each arc-lamp inthis system is regulated by mechanism located inside of the lampitselfor by this mechanism in conjunction with auxiliary resistance orreactance, and the general practice is to supply to the circuit aconstant potential. lVhere these lamps are not fed from a low-potentialcircuit, it is necessary to introduce a step-down constant-potentialtra-ns'fori'ner between a set of high-tension circuit-wires. Thehigh-tension wires above referred to take the place 0f the low-tensioncircuit, and in this event the general plan of operation is the same,with the exception that the lamp is supplied with the proper energyrequired by the interposition of a reduction-transformer between thelamp and the circuit.

Another system is the arrangement of the arc-lamps in series, thecircuit containing these lamps being fed from the secondary of aconstant-potential transformer fed by a constant-potential dynamo. Inthis arrangement the control of current flowing in the circuitiseffected by means of regulatingresistaneeor iuductances in either theprimary or secondary circuits. As is wellknown, the condition of anarc-lighting series circuit is a very unstable one, many causes enteringto make the effective resistance of the circuit a widelyvaryingquantity. By reason of this wide variation in the resistance of thiscircuit the variation of the current (providing that thc potentialsupply is constant) is as great as is the variation of the resistance.The successful operation of the circuit, however, is dependent on themaintenance of the current flowing at a constant value. Manualregulation of the switchboard is therefore resorted to to procure thisconstant value, which re- ICO quires the attention of a skilledelectrician, whose duties are to plug in or plug out, as the circuitdemands. The circuit being thus dependent upon the strict attention toduty7 on the part of the attendant, it willbe seen that very wideirregularities in the operation of the circuit might easily arise.Further than this, serious consequences might follow from thesevariations in that the partial or possibly the total destruction byburning out might result not only to the lamps but to the transformerfeeding the circuit, with the further objectionable result of a verywide variation of the current demand upon the dynamo. These variationsare sometimes so sudden and of such wide range as to render the manualmanipulation of the switchboard im possible with respect to the controlthereof by the attendant within safe points.

Another system for the use of alternating arc-lamps in series makes useof what is known as a constant-current transformer, operating on aconstant-potential circuit. This transformer is so constructed as tofurnish a constant secondary current through the medium of the automaticintroduction of a large magneticleakagein the transformenthat is, thetransformer is so constructed as to limit the amount of magnetic linesof force which will effectively thread themselves through the secondarycircuit. lransformers maybe constructed to accomplish this end inseveral ways, and it is not deemed necessary to explain the same here,and such transformers can, if built properly, effeetually maintainpractically constant current in the lamp-circuit within wide limits. Indoing this they answer the practical requirements, and did they notinvolve certain objectionable features outside of the lamp circuit wouldbe a very satisfactory solution of the problem. Vile will refer to a fewof the iinportant objections to this system:

First. The so-called power factor of the current which such atransformer as thisdraws from the dynamo is low at practically alltimes, decreasing in value with the amount of magnetic leakage. lt is atits best value when the arc-circuit feeding from the secondary isoperative under normal conditions, for which this immediate system wasdesigned. Should for any reason the resistance of the arc-circuit fallbelow the normal value, the consequence will be an increase of themagnetic leakage in the transformer and a consequent decrease of thepower factor of the current supplied by the dynamo. It is detrimental tothe satisfactory pressure regulation of an alternating dynamo to have acurrent of low power factor taken Vfrom the dynamo in so far as thedynamo is concerned, chiefly by the fact that it becomes diflicult tomaintain a constant pressure at the brushes, and, further, that thecapacity of an average alternating-current dynamo is very innendecreased under such conditions. In other words, it is possible tooperate an alternatcarga/ee ing-current dynamo in extreme cases withfifty per cent. more load when the power factor is high than can beaccomplished when the power factor is low, and therefore it is of greatadvantage to the central stations to have the power factor of theirservice as high as possible. lf the pressure regulation of the dynamo ispoor by reason of a variable and low power factor of the current takenfrom it, it becomes disadvantageous to operate incandescent lamps fromthe same dynamo, as it is well known that incandescent lamps operateefficiently and with long life only when the pressure of the currentsubjected to them is maintained practically constant.

Second. '.lhe ratio of current in the primary winding in the transformerto the current in the secondary winding of the transformer remainspractically constant regardless of the condition of the arc-lightcircuit external of the transformer-that is, it matters not as to theamount of current flowing through the windings of the transformerwhether there be one-half or all of the lamps of the arc-circuit ineffective operation. The result of this feature of the transformer isthat the waste of energy in the copper windings thereof is practically aconstant quantity regardless of the amount of effective work which isbeing done in the external secondary circuit thereof, and therefore theenergy losses in the transformer are practically constant at all times.The fact that there exists in such a transformer the feature of theamount of current being always constant contributes to the increasedreaction upon the dynamo itselfthat is,the effect of the decrease ofpower fact-or of the current taken from the dynamo upon the regulationof the dynamo is worse when little work is being done in the arc-lightcircuits than when a great amount of work is being done. if a smallamount of work were done in the circuit and lthe amount of current takenfrom the dynamo were decreased proportionately, the effect on the dynamowould not be so Serious even did the power factor of the lessenedcurrent decrease. As it is, however, there is the double effect of thecurrent demand remaining large when the work being done is small and thepower factor decreasing with the same amount of current when the workbeing done is small.

ln our system the power factor remains constant at practically all loadsand at a high value, while the demand of current from the dynamo bearsan almost constant ratio to the amount of work being done in thearc-light circuit.

Another system has made use of a constantpotential transformer with anexternal resistance or reactance automatically governed. L lVhereresistance is used, a high power factor is always maintained; but theloss, or rather the power consumed by the system, is always the maximumenergy required for the whole circnit-that is, if the effective circuitof arclamps does not require the maximum energy IOO IIO

by reason of several lamps being temporarily or otherwise removed fromthe circuit the energy which these removed lamps from the circuitrequire is taken up in the auxiliary resistance. Such a system is highlyinefficient. Where a reactance is inserted, it accomplishes practicallythe same thing within the transformer and with all the attendantobjectionable features ef a constant-current transformer above referredto.

Our invention therefore consists in the use of a constant-potentialtransformer, the winding thereof being built in steps. yWe introduceautomatically-controlled regulating devices which vary the amount ofwinding of the transformer in actual use in proportion to therequirements of the circuit. rlhis automatic controlling device is soarranged that the current which flows in the winding of any and all suchportions in actual use will be maintained practically (so far as thesecondary is concerned) constant, being the amount required for theoperation of the external arclighting circuit or other circuit. lt iswell known that a constant-potential transformer gives out from itssecondary in energy the same amount within a small. per cent. as issupplied to the primary in energy. The amount of energy, real orapparent, in either primary or secondary circuit is proportionate to theproduct of the pressure of the current in both cases. lt is ourintention to take from the secondary a constant current, and thereforethe amount of energy which we draw from the secondary will beproportionate to the pressure which we require to use, and the amount ofsuch pressure will be immediately in proportion to the number of stepsof the secondary winding of which we make effective use. The totaldemand of energy from the dynamo will thereby be proportioned to theamount of pressure which we take from the secondary circuit. Since thesecondary current is constant and since the primary gressure isconstant, it follows that the amount of current which we take from thedynamo will be proportionate to the amount of pressure made use of onthe secondary side of the transformer. It is well known that atransformer constructed for a constant-pressure reduction is one inwhich the power factor of the current in the primary circuit ispractically the saine as the power factor of the current in itssecondary circuit. This being the case, the power factor of thecurrentsupply taken from the dynamo will with our arrangement be thepower factor of the current flowing in the arc-li, i;hting circuit. ltis also well known that the power factor of an arc-lamp whereinductances or reactioncoils are not introduced is relatively high,being approximately .85 to .90. if we introduce no auxiliaryreactance-coil or other form of auxiliary resistance devices, the powerfactor of the current taken from our transform er will be practically S5to .90, and therefore the power factor of the current taken from thedynamo will be substantially the saine-that is, .S5 to .SO- and will bepractically constant for all conditions of resistance in the secondarycircuit, since the only variation of resistance in the arc-lightingcircuit will arise from the cutting in or cutting out of lamps.

To sum up briefly the advantages accomplished by the use of our system,we may recapitnlate as follows:

First. The current drawn from the dynamo always has a high power factorand is in proportion to the number of lamps burning` in the arc-circuit.

Second. The arc-circuit is at its maximum efficiency if we introduce noresistance to take the place of lamps which temporarily or otherwise arecut out of the circuit.

Third. The transformer is at its maximum efficiency as the lossestherein are in a measure proportionate to the effective work being donein the circuit.

ln the accompanying drawings, to which we will now refer asillustratingseveral ways of carrying out our improved system, we have shown awell-known construction of switch, to which we lay no claim in thispresent application, and while we have illustrated a lamp-circuit insaid drawings we do not wish te be understood as limiting theapplication of our system or proposed arrangement of devices toarc-lighting circuits alone, as it is obvious that there are other kindsof service in which the same conditions exist in which our system can beused with good effect. In fact, any circuit where a constant current isrequired and a variable resistance is met can be with equalelfectiveness operated from a constant-potcntialtransfornierbyourmethod,it being automatically controlled by the current flewing,the apparatuseffectually protecting itself from damage of any sort, such as burningout or otherwise.

ln Fig. l of the drawings, 'l indicates a transformer etween the dynamoand light-- ing-circuit. A constant potential is applied to the primarywinding P, developing practically a constant potential in the secondarywinding S. This secondary winding is so wound that taps are brought outat interinediate points between the first and last ends, as at 0, l, 2,S, il, 5, G, 7, and S. rlhese intermediate points (indicated by the tapsO to 8, inclusive) are connected to terminals or corresponding points ona switchboard A, said terminals being in Fig. l preferably arrangedconcentrically to the axis of rotation of a switch-arm B. Thisswitch-arm carries two contact-points l) and D', cooperating with theterminals of the taps and so arranged with relation to each other and tosaid terminals that at least one of said contacts isin engagement with aterminal. Contacts Z) and cooperate at their inner ends with rings o andc, from which lead wires to an iinpedeiicecoil l, tapped at its centerby the supply-wire s of the lainp-circnit. Switch-arm B has con- IOO IIO

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joined to it a beveled gear C, with which meshes a pinion D, rigidlymounted on shaft E, supported in suitable bearings. Shaft E carries afriction-roller F at its other end, which roller bears upon adisk-plateG, revolubly mounted in an arm H, suspended from thearmature-shaft of a small motor M or other source of power, so that saiddisk will be constantly rotated at an even rate of speed. In theconstruction shown in Fig. l disk G is driven by a belt running overapulley on the armature-shaft, and the motor is supplied with energyfrom the primary circuit, although it is obvious that the motor can be'adirect-current motor and supplied from such a source of energy. Arm H,carrying disk G, is designed to be swung upon its pivotal support, asindicated by dotted lines, and to effect this lateral position of saiddisk we arrange cables R on each side of support H, which cables, attheir opposite ends, are connected to plungers n ando of the solenoids Nand O.

The solenoid O receives its current from either the secondary or primarywinding of the transformer, and when the transformer is in operativeconnection with the dynamo-circuit the magnetic strength of solenoid Ois practically constant. XVe may, if we desire, utilize a step-downtransformer T, whose secondary is in series with the solenoid O. For thesake of distinction we will call the circuitin which the solenoid isarranged an auxiliary circuit of constant potential, regardless of thesource from which it is derived. The solenoid N is in series with thearc-lamp circuit, and therefore its magnetic strength depends on theamount of current iiowing in this circuit. For the sake of distinctionwe will call the circuit in which the solenoid N is arranged a circuitof varying potential with constant current. le provide the plunger a tocooperate with this solenoid with a spring L.

ln operating the system it is intended and desired that'the combinedstrength of solenoid N and the spring attached to its plunger shallexactly equalize the strength of the plunger in solenoid O when thelamp-circuit receives the proper amount of current. Should the strengthof N and L decrease, the plunger o will be drawn farther out, whichswings the disk G to one side, so as to rotate the switch-arm B in suchdirection as to cause said switch to increase the total pressure betweenpoints e0 and 50 of the arc-lamp circuit until the current in thesolenoid N and the lamp-circuit runs up to such strength as to enablethe solenoid N to draw the disk G back to its central position, whereequilibrium is established. Should solenoid N become too strong, itsplunger is drawn down and the reverse rotation of the switch-arm Bfollows, cutting down the pressure between 40 and 50. As shown in Fig.l, we prefer to arrange impedence or choking coils around each lamp inthe circuit which are in shunt or in parallel with the lamp, so thatshould a lamp be temporarily extinguished it will not affect theoperation of the remaining lamps in the system. Should a break in thecircuit occur, say, at 45, this would run the pressure up between 40 and50 to the full capacity of the transformer, and the solenoids wouldautomatically adjust themselves to such changed conditions and operatethe switch which controls the secondary circuit of said transformeraccording to the position of the terminals of its taps or steps.

A. short-circuit in the system is anothercontingency which is taken careof by our improved arrangement. Vere no protecting devices introducedinto the system, a short-circuit would reduce the pressure between li0and 50 to zero, in which event the solenoid O would operate to turn theswitch to its zero position or position of starting, as shown in Fig. l.A third condition which would also be taken care of by our improvedsystem would be when the transformer is cut out of circuit, renderingboth opposing solenoids ineffective. Under such circumstances the springL operates to return the switch-arm to Zero for the next start.

lt will be seen from the above that the secondary of ourconstant-potential transformer is stepped, each lead-out or step havinga terminal in the path of a switch; that said switch is automaticallycontrolled to contact with various terminals, according to the conditionof the secondary circuit; that such controlling means comprise opposingsolenoidsone in the lamp-circuit and the other fed from the secondary orprimary circuit proper-said solenoids being so influenced under certaincircumstances as to throw into or out of operative position certainmechanical devices to operate said switch in either direction or tocause said switch to assume a stationary position; that independent ofthis automatic control during the period in which the systcm isoperating means are also provided acting independently of the system forautomatically restoring the system to a normal position in readiness foranother start.

ln the event that the pressure in the secondary circuit is run up to thefull capacity of said secondary the segment or gear with which thepinion meshes is carried around until its last tooth passes the pinion,when the switch-arm rests on the terminal marked 8, being the fullcapacity of the machine, and is there held. If for any reason thepressure in the secondary circuit is still insufficient to bring thesecondary circuit to the normal amount, the switch can be turned nofarther, as the gear C, as shown in Fig. l, is provided with a blankportion-that is, a few teeth are removed to 1n utilate said gearand whenthe pinion D reaches said mutilated portion it will rotate idly. Thepinion reaches this mutilated portion when the switch-arm is at itseXtreme limits, as when resting on terminals 0 and 8. (Shown in Fig. l.)The stop hX is provided on the lower face of arm B, as shown in Fig. l",and this stop coper- IOO IOS

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and starts on its backward rotation until equilibrium is restored in thesystem and the switch-arm brought to a stationary position, when it canbe again moved the full capacity of the secondary, as before described.1f, however, the movement of the switch-arm continues until it reachesthe zero position, it will be arrested by the engagement of theprojection ox with the springa, at which time the mutilation in the`gear will be in register with the pinion, and the pinion will operateidly. Spring Qc now exerts its energy to engage the mutilated gear withthe pinion immediately that the secondary is cut in, so that thesolenoids will be energized to reverse the rotation of the pinion. Thisoperation will be readily understood when it is borne in mind that thedisk operates the pinion in opposite directions, depending upon thepreponderanceot energy in the respective solenoids, and the pinion,being in engagement with the gear, will rotate the same until themutilated portion of the gearisreached,when the pinion, if rotationthereof continues, will rotate idly, merelyslipping over the last toothit had previously engaged. The springs x and so', when the switch-arm isin either of its extreme positions, tend to force said switcharm in suchdirection that the tooth last engaged by the pinion will he in readinessto again engage the pinion immediately that the pinion commences itsbackward rotation.

The above conditions prevail with respect to the construction shown inFig. 1 of the drawings; but it may be desirable at times to run thecapacity of the secondary even higher by reducing the number of windingsof the primary after the secondary has reached its full capacity, and toaccomplish this we provide terminals Q, 10, and 11 in the path of theswitch-arm B, as shown in Fig. 2, which are engaged by switch-tongues band b", which switch-tongues engage at their inner ends withconcentrically-arran ged rings c" and c', both of which form terminalsfor the returnwire of the dynamo-circuit and are connected with animpedance-coil 1' in substantially the same manner as the impedance-coilI. It is obvious by this arrangement that the secondary should be keptin circuit while the primary is being cut down, and this is accomplishedby extending the terminal 5 the full distance of the movement of theswitch-arm, and, further, as the primary must be kept in circuit whilethe secondary is cut in the iirst terminal ofthe primary with which theswitcharm engages is continuous and cooperates with the switch-arm untilthe separate terminals of the secondary are passed, when thev separateterminals of the primary are then in readiness for individualcooperation with the switch-arm.

It is obvious that while we have shown and described separate operationsfor cutting in and cutting out the secondary and primary windings insuccession they could he cut in and cut out contemporaneously oralternately and accomplish the saine result.

Impedance-coils l and l' act merely as choking-coils for the purpose ofpreventing a short circuit across the switch-arm in the contact of theswitch-arm with separate terminals. As the function and operation ofthese impedance-coils are well understood as used in this connection, itis not deemed necessary to go into a detailed description thereof here.

The operation of the system shown in Fig. 2 is substantially the same asthat described with relation to Fig. l-that is, varying pressure in thesecondary will so regulate the energy in the solenoid that the switch 13is caused to move in one direction by said solenoid and in the oppositedirection by the spring B" to cut in or cut out certain steps of thesecondary winding. The solenoid N (shown in Fig. 2) may be energized bythe current iowing in the lamp-circuit alone or by a combination of thecurrent flowing in the lampcircuit together with a current derived by apressure connection to either the primary or secondary windings of thetransformer in a variety of ways.

Another method of carrying out our invention is illustrated on the thirdsheet of the drawings, in which the sections of the secondary are turnedagainst themselves to neutralize each other, which neutralization whenremoved cuts in the various sections in succession and so builds up thepressure in the external secondary circuit.

ln Fig. 3 we have illustrated a scheme in which there are seven sectionsin the secondary, three of which may be reversed, a switch being usedwhich is composed of three independent switches X, Y, and Z, connectedin series, and a single switch-tongue cooperating therewith. When thesecondary circuit is under full pressure, the switch-tongue is in theposition shown in this figure. The current then enters plate 19 ofswitch Z, passing' to plate 17b via portion 1S, then to plate 16 andthrough the section of the secondary coil back to plate l5 and viamember 14C to plate 13, from which it passes through wire 2O to plate 19of switch Y, thence to plate 17h, through member 18 on theswitch-tongue, through the coil-section of the secondary controlled byswitch Y, and back again to plate 15, and thence through member 14 toplate 13, and iinally through the switch X and coil controlled by it,and then through the solenoid to the lamp-circuit and the four remain-ICO IIO

G scarse ing coils ot the secondary. Should the resistance in thearc-lighting circuit be reduced, the switch--arm is automatically moveduntil the contact members 14 and 18 rest on the plates 15 and 17 etswitch Z. The current then traces the following path, viz: plate 1t),member 1S, plate 17, resistance o", from plate 17 to plate 15, throughthe coil of the seeondary controlled by switch Z, bach to plate 1G,through resistance fr and plate 15, through member 111 and plate 13 andvia wire 2O to the remaining switches, coils, or circuits, as before.The resistances r and o are sut'ticient ot' themselves to neutralize theeffects of a portion of the secondary windings and compensate for thereduced resistance in the lighting circuit. Another position of theswitch is where each contact member on the arm engages two terminals atonce-that is to say, referring to switch Z, when the contact member 1sbears on plates 15 and 15 at the same time and member 1S similarly bearson plates 17L and 171. ln this position the coil controlled by switch Zis practically cut out-that is, the resistance r prevents a completeshort circuit in said coil. At the same time the bridge-wire from plateI5 to plate 17, plate 17, resistance r', plate 17, member 1S, and thebridge-wire from 17 to 16 otter a second path for the short circuit anda current from the secondary coil. The current entering and passingthrough plate 19 passes to 17", through resistance fr' to plate 15, andthen to plate 13 and on to switches Y and Z and the other circuits, asbefore described. When the switch-arm is resting on the terminals 17 and19 and 13 and 16, it is in the starting or neutral position, in whichthe current passes through the following parts in the order-given: 19 1S17 15, the coil controlled by the switch, 1G 13 20, and the switches Yand X. In this position it will be noticed that the resistances are cutout of the secondary circuit, the two short-eircuited paths for the coilare removed, and the current passes through the coil in a reverseddirection, which causes a neutralization of one of the remaining coilsof the secondary, so that when the switch-arm is in similar terminals ofthe switches Y and X the secondary electromotive force is practicallyzero and no current would ilow were it not for the effective section inthe secondary winding. The switches Y an X operate similarly to switchZ, and the switches come into action one after the other,so that theinternal and external circuits are gradually built up or reduced,according to requirements.

According to the system shown in Fig. 3, wherein seven sections areemployed in the secondary, three of them being controlled by switches,the reversal ot one ot these sections under normal running conditions isequivalent to cutting outtwo sections, the reversal of two of saidsections is equivalent to cutting out tour sections, and the reversal otthree is equivalent to cutting out six sections, the seventh beingprovided to prevent short circuit in the secondary. lt is obvious thatin all of these systems a choking-coil may be connected in series withthe arc-lamp circuit, as shown at l in Fig. 2.

Vile are aware that many minor changes in the arrangement, construction,and combination of several parts of our s istem can be made andsubstituted without in the least departing from the nature and principleof our invention.

Having thus described our invention, what we claim, and desire to secureby Letters Pat.- ent, is-

1. The combination with a constant-poten tial transformer and itscircuits, one of said circuits being an auxiliary circuit of constantpotential, and another a circuit of varying potential with constantcurrent, said transformer having independent primary and sccondarywindings, ol a source oi' supply 'for said transformer in the form of analternating or pulsating current, a switch or switches in a circuit orcircuits of said transformer, and automatic regulating means l'orcontrolling said switch or switches, which means is electricallyenergized by the auxiliary constant-potential circuit and the circuit otvarying potential with constant current; substantially as described.

2. he combination with a constant-potential transtormer and itscircuits, one or" said circuits being` an auxiliary circuit ot' constantpotential, and another a circuit otl varying potential with constantcurrent, said transformer having independent primary and secondarywindings, ot a source ot supply for said transformer in the form of analternating or pulsating current, a switch or switches in a circuit orcircuits ol' said transformer, and automatic regulating means forcontrolling said switch or switches in either direc tion, which means iselectrically energized by the auxiliary constant-potential circuit andthe circuit of varying potential with constant current; substantially asdescribed.

The combination with a constant-potential transformer and its circuits,one of said circuits being an auxiliary circuit of constant potential,and another a circuit of varying potential with constant current, saidtransformer having independent primary and secondary windings, ot asource ot supply tor said transformer in the form of an alternating orpulsating current, a switch or switches in a circuit or circuits of saidtransformer, solenoids which are separately energized by the auxiliaryconstant-potential circuit, and the circuit ot' varying potential withconstant current, for operatin said switch or switches, wherebypreponderating pressure in either ot the circuits will cause one of thesolenoids to dominate the other and throw the switch in the properdirection to establish equilibrium; substantially as described.

The combination with a constant-potential transformcr and itscircuits,one of said circuits being an auxiliary circuit of constant po-TOO IOS

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esmas tential, and another a circuit of varying potential with constantcurrent, said transformer having independent primary and secondarywindings, of a source of supply for said trailsformer in the form of analternating er pulsating current, a switch or switches in a circuit orcircuits of said transformer, solenoic which are opposed to each other,and which are separately energized by the auxiliary censtant-potentialcircuit, and the circuit of varying potential with constant current, foroperating said switch or switches, whereby preponderating pressure ineitherof the circuits will cause one of the solenoids to dominate theother and throw the switch in the proper direction to establishequilibrium; substantially as described.

5. rlhe combination with a constant-potentialtransformeranditscircuits,oneofsaid circuits being an auxiliary circuitofconstant potential, and anothera circuitof Varying potential withconstant current, said transformer having independent primary andsecondary windings, of a source of supply for said transformer in theform of an alternating or pulsating current, of a switch for regulatingthe effective portions of said transformer, positive mechanical meansfor operating said switch, and solenoids which are energized by thecircuits of the system for causing said positive mechanical means tomove the switch in different directions or permit the switch to remainstationary; substantially as described.

C. The combination with a constant-potential transformer and itscircuits,one of said circuits being an auxiliary circuit of constantpotential, and another a circuit of varying potential with constantcurrent, said transformer having independent primary and secondarywindings, of a source of supply for said transformer in the form of analternating or pulsating current, of a switch for regulating theeffective portions of said transformer, mechanism normally in positionto throw said switch, and solenoids energized by the circuits of thesystem rendering said mechanism operative with respect t0 said switch;substantially as described.

7. The combination with a constant-potential transformer and itscircuits,one ofsaid circuits being an auxiliary circuit of constantpotential, and anotheracircuit of varyingpotential with constantcurrent, said transformer having independent primary and secondarywindings, of a source of supply for said transformer in the form of analternating or pulsating current, of a switch for regulating theeffective portions of said transformer, mechanism normally in positionto throw said switch, and solenoids energized by the circuits of thesystem rendering said mechanism operative with respect to said switchand variablyadjusting the speed of the switch in either direction it maybe moved; substantially as described.

S. The combination with a constant-potential transformer and itscircuits, one of said circuits being an auxiliary circuit of constantpotential, and another a circuit of varying potential with constantcurrent, said 'transformer having independent primary and secondarywindings, of a source of supply 'for said transformer in the form of analternating or pulsating current, a switch for regulating the effectiveportions of said transformer, mechanism for throwing the switch,solenoids which are energized by the circuits of the system for causingsaid mechanism to engage with or be disengaged from the switch, andmeans for limiting the movement of said switch and throwing the same outof engagement with said mechanism; substantially as described.

i). The combination with a constant-potential transformer and itscircuits, one of said circuits being an auxiliary circuit of constantpotential, and another a circuit of varying potential with constantcurrent, said transformer having independent primary and secondarywindings, of a source of supply for said transformer in the form of analternating or pulsating current, of a switch for regulating theeffective portions of said transformer, mechanism for moving said switchin either direction, solenoids which are energized by the circuits ofthe system to cause the engagement of said mechanism with said switch temove the same in either direction, depending upon the preponderance ofstrength in either of said solenoids, and means for rendering saidmechanism inoperative with respect to said switch when the limit ofmovement is reached at either extreme; substantially as described.

10. rllhe combination with a constant-potential transformer and thesource of supply therefor in the form of an alternating or pulsatingcurrent, of a switch for regulating the effective portions of saidtransformer, a gear attached to said switch, a pinion meshing with saidgear, a friction-wheel mounted on the pinion-shaft, a disk with whichsaid frictionwheel engages, means for rotating said disk, and solenoidswhich are energized by the system, and which exert their energy to causea relative movement between said frictionwheel and disk, so that thepinion will operate its meshed gear, and threw the switehin onedirection or the other; substantially as described.

ll. The combination with a constant-potential transformer and itscircuits, one of said circuits being an auxiliary circuit of constantpotential, and another a circuit of varying potential with constantcurrent, said transformer havingindependentprimary and secondarywindings, of a source of supply for said transformer in the form of analternating or pulsating current, of a switch for cutting in or cuttingout sections of the primary or secondary windings of said transformer,and automatic regulating means for controlling said switch, which meansis electrically energized by the auxiliary constant-potential IOC IIO

circuit and the circuit of varying potential with constant current;substantially as described.

l2. The combination with a constant-potential transformer and the sourceof supply therefor in the form of an alternating or pulsating current,of a switch for cutting in, cutg ting out, or reversing the sections ofthe secondary winding of said transforn'ier, and automatic regulatingmeans for controlling said switch, which means is electricallyenergizedby the system.

13. The combination with a constant-potential transformer and itscircuits, one of said circuits being` an auxiliary circuit of constantpotential, and another a circuit of varying potential with constantcurrent, said trans former having independent primary and secondarywindings, of a source of supply for said transformer in the form of analternating or pulsating current, of a switch for cutting in or cuttingout sections of the primary winding of said transformer, and autolnaticregulating means for controlling said switch, which means iselectrically energized by the auxiliary constant-potential circuit andthe circuit of varying potential with constant current, substantially asdescribed.

11i. The combination with a constant-potential transformer and'itscircuits, one of said circuits being an auxiliary circuit of constantpotential, and another a circuit of varying potential with constantcurrent, said transv former having independent primary and secondarywindings, of a source of supply for said transformer in the form of analternating or pulsating current, of a switch for controlling theeffective portions ot` said transformer, automatic regulating means forcontrolling said switch, which means is electrically energized by theauxiliary constant-potential circuit and the circuit of varyingpotential with constant current, and shunt or parallel impedance-coilsaround each translating device in the circuit; substantially asdescribed.

l5. The combination with a constantpotenscarse tial transformer and itscircuits, one of said circuits being an auxiliary circuit of constantpotential, and anothera circuit of varying potential with constantcurrent, said transformer having independent primary and secondarywindings, of a source of supply for said transformer in the Aform of analternating or pulsating current, of a switch for controlling therelations of the portions of said transformer to each other, automaticregulating means for controlling said switch, which means iselectrically energized by the several circuits ot the system, shunt orparallel impedancc-coils around each translating device in the system,and an impedance-coil in series with the circuit of varying potentialwith constant current; substantially as described.

1G. The combination withaconstant-potential transformer and itscircuits, one of said circuits being anauxiliarycircuit of constantpotential, and another a circuit of Varying potential with constantcurrent, said transformer having independent primary and sec ondarywindings, of a source of supply'for said transformer in the form of analternating or pulsating current, said secondary windings being arrangedin sections, of a switcharm cooperating with the terminals of saidsections, resistance or impedance coils which are cut in or out by saidswitch-arm for increasing or decreasing the effectiveness of saidsections, whereby one or more of said sections are partially or whollyneutralized by said resistance, and means energized by the auxiliaryconstant-potential circuit and the circuit of Varying potential withconstant current for automatically operating said switch substantiallyas described.

In testimony whereof we hereunto affix our signatures, in the presenceof two witnesses, this 25th day ot' February, 1899.

KVALDO A. LAYMAN.

FERDINAND SCI'IXVEDTMANN.

Witnesses:

F. R. CoRNwZALL,

A. S. GRAY.

